The deficits in spontaneous gaze monitoring of others are well documented in ASD and constitute a part of a complex social-cognitive deficit in joint attention skills. Little is known, however, about the extent and the underlying mechanisms of these deficits. This research will investigate gaze perception in children under the age of 3 years diagnosed with an autism spectrum disorder (ASD). It will target skills that emerge in typical development in the first months of life and remain functional throughout adulthood, namely covert attentional cueing by perceived direction of gaze (i.e., reflexive joint attention). These skills will be measured using an experimental procedure in which latency of eye movement to peripheral targets following presentation of directional cues is assessed. Two preliminary studies suggest that this method is highly effective in studying young children with ASD and that there are important similarities as well as differences in gaze processing between ASD and TC groups. The extent of these differences and their underlying mechanisms remain to be explored. Toward this end the following Specific Aims are proposed (1) to test the hypotheses that children with ASD under 3 years of age process information about eye gaze direction differently than children with developmental delays (DD) and typically developing children; (2) examine the relationship between the performance on the perceptual cueing tasks and severity deficits in social functioning: (3) to examine the relationship between the attention cueing measures and diagnosis. Following successful completion of this work we will have elucidated some of the mechanisms underlying deficits in spontaneous gaze monitoring in autism. Our future research will focus on applying this knowledge to devising simple behavioral methods of identifying infants at risk for autism as well as intervention procedures aimed at the specific social-cognitive deficits observed in early onset autism.